Device for cleaning filter tubes



Sept. 13, 1932. CANNON 1,877,723

DEVICE FOR CLEANING FILTER TUBES O rigina1 Filed 00? 2, 1929W/////////AIZ HUGH HARLEY CANNON v INVENTOR T TORNE) Patented Sept. 13,1932 'UNITED STATES .ATENT OFFICE HUGH HARLEY CANNON, OLE LOS ANGELES,CALIFORNIA, ASSIGNOB. TO CANNON- PRUTZMAN TREATING PROCESSES, LTD., 0]?LOS ANGELES, CALIFORNIA, A CORPO- RATION OF CALIFORNIA DEVICE FORCLEANING- FILTER' TUBES Original application filed October 2, 1929,Serial No. 396,397. Divided and this application filed September 24,1930. Serial No. 484,127.

This application is a division, of my copending application, Serialbio-396,897, filed October 2, 1929, under the title Method 0 cleaningfilter tubes.

My invention relates to the art of. filtering comminuted solids fromliquids, and to that branch of the art which relates to the use oftubular filtering elements fed from the inside. 7

My invention relates specifically to a manner of and a variety of meansfor so releasing from the cloth the tubular cake of solids which formswithin such tubular filtering elements as toenable it to be readilydischarged from the tube.

When tubular filtering elements are fed inside with a mixture of liquidandv comminut-ed solid, the liquid portion .of the suspension passesthrough the Wall of the element and the solid is deposited on the insidein a layer which gradually increases in thickness. I

If filtration be long enough continued, this it is customary toterminate the filtering stage of the operation some time before thiscomplete closure is reached, for instance, at a point where thethickness of the cake is equal to about half the radius of the tube.

When the filtration is finished, that is, when the cake has attained thedesired thickness,

it is customary to withdraw the supply of suspension from the inside ofthe tube andto blow steam, air or other gas through the cake until it isdried out so far as is possible. A

washing operation may be interposed between filtration and drying out ifthe liquid entrained in the cake is either valuable or viscous.

After drying out the cake, it is customary to expose an end of the tubeby any suitable means and to apply air under pressure to the outside ofthe tube, by which pressure,if the pressed to that slightly smallerdiameter tube is of cloth or other flexible material, the

which will enable it to be readily discharged from the tube, by gravity'if the tubebe vertically set or by extrusion meansif the tube be in ahorizontal position. i

The fallacy in this theory is that the tubular cake is built up undersuch conditions as to give it the greatest density consistent withthenature of itscomponent material, the-cake forming by gradual accretionof suspended particles which, by the flow of liquid from the inside tothe outside of the cake, are wedged into every available crevice andcompacted to the last degree. Further, the tubular cake forms'a perfectarch in each direction so that its distortion by outside pressure canfollow only from crushing and never from bending. V

It follows that unless the cake is very thoroughly dried out and unlessit is composed of rounded grains so as to form a friable mass, thecompressive effect of such outside pressures as can be tolerated ina'press of feasible strength will produce an insigmfithe most favorableconditions; cake will grow toward the center until it fills the tube,but to enable the cake to be removed I have discovered that if a.longitudinal section be removed from such a tubular cake,-

so that the arch is, as it were, unkeyed,a bending effect is broughtinto play by which, at much reduced pressures, the cake may bethoroughly broken down and made amenable to ready discharge by means ofgravity or an air blast directed longitudinally 1 through the tube.

The'narrow strip of cloth exposed by the removal of the longitudinalsection of the cake is forced into the slot thus formed, crumbling itsedges, and this failure is rapidly transmitted around the entire arch,with damage the cloths'if persisted in,'I prefer.

to use one or the other of the devices illustrated in the attacheddrawing, in which Fig. 1 illustrates, in Vertical elevation, a devicefor forming and relievinga longitudinal slot in atubular filter cake,the relieving movement being effected by a longitudinal movement of ahandle situated outside the press;

Fig. 2 illustrates, in cross section, a portion of the cake and the barwhich forms the slot in Fig. 1. v Fig. 3 illustrates, in Verticalsection, a cle- Vice for relieving a longitudinal slot in which therelieving movement is effected by a rotating movement of a projectinghandle, and Fig. a illustrates, in cross section, a portion of thecakeand of the vane which forms the slot in Fig. 3. 7

Referring to all four figures, 10 is a portion of the tubular filteringelement appearing in section, and 11 a portionappearing in elevation,the opposite side of each tube being broken away. 1212 are the tubesheets i in which the ends of the tubes are fixed. 13

is a broken portion of the upper head orcap comprising part of the shellsurrounding the filtering elements and enclosing the tube ends, thecorresponding lower portion of the shell not being shown. l l is astuffing box .bar17 extends both above and belowthe opposite ends of thetube and is supported from the slotted bars by the flat headed studs 18,the shanks of which slide freely in the slots. A projection 19 at theupper end of the bar carries a pin 20 on which the link 21 is swivelled,the upper end of this link being correspondingly swivelled at the lowerend 22 of the actuating rod 23, which passes through stuffing box ll andterminates in a T handle 24. I

On raising this handle to its upper limit, the pins 18 slide upwarduntil the bar 17 is brought into contact with the cloth which forms theinner layer of the filtering element 10. The press being operated withthe bar in this position, as indicated at 1?, cake forms around theinside of the tube except for the space occupied by the bar. Filtering,washing and drying being completed, the lower end of the tube is exposedin any suitable manner and the handle 24 forced down, thus moving thelongitudinal bar to the position shown at 17 B. This movement opens aslot of a width equal to that of the bar, by means of which slot thecrushing of the cake may be accomplished by outside'pressure asaforesaid.

Referring now to Figs. 3 and 4, 2525 are formed on the lower end of theactuating rod 30, which passes through the stufling box 14, andterminates in a T handle 31. The round bar 27 is equipped with alongitudinal vane 32 which, by turning the handle 31, may be revolved tothe position 326. The purpose of the square end and socket 2829 is toenable a swinging press head (13) to be swung upward without affectingthe position of the bar assembly.

During the filtering operation the vane is turned down against the clothand cake will build up over it to more or less the position indicated at33. The filtration, washing and drying being completed and the tube endexposed, a quarter turn of handle 31 will bring the vane to the position32?), and in doing so will break out the portion of the cake indicatedat 34. On then applying outside pressure to the cake, it will crumblefrom the side opposite the position of the vane, if not from both edges,and its destruction will rapidly and completely follow.

I prefer the form of apparatus shown in Figs. 3 and 4, as being cheaper,requiring less effort and as opening a wider slot or hiatus in the cake.It will be evident, however, that-numerous mechanical movements might beadapted to produce the same result, and I therefore claim, not merelythe preferred device, but also the method or manner of breaking downtubular filter cakes 'described and limited in the appended claims.

My method will be found very useful in handling aqueous cakes of a toughor sticky nature which cannot be made to flow and which are not readilysubject to compression, and, particularly, to the cakes resulting fromthe filtration from various kinds of oil of such bodies as diatomaceousearth, decolorizing clays and dry treating chemicals.

I claim as my invention:

1.-A device for preparing tubular'filte cakes for removal from tubularfilter elements, comprising: a'substantially straight longitudinal barnormally positioned adjacent the inner surface of said element, andmeans for movingv said bar away from'said inner surface to create anopening through said cake through the length of said cake.

2.,A device for preparing tubular filtercakes for removal from tubularfiltering elements, comprising: a substantially straight longitudinalbar normally positioned parallel and adjacent the inner surface of saidelement, and means for revolving said bar away from said inner surfaceto create an opening through said cake through the length of said cake.

In witness that I claim the foregoing, I have hereunto subscribed myname this 27th day of August, 1930.

HUGH HARLEY CANNON;

